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  <title>Document</title>
</head>
<body>
  <script>
let score=prompt('请输入您的分数')
    if(score >=90){
      alert('A')
    }else if(score >=80 && score <90){
      alert('B')
    }else if(score >=70 && score <80){
      alert('C')
    }else if(score >=60 && score <70){
      alert('D')
    } else{
      alert('E')
    }
    
  </script>
</body>
</html>